The present invention relates to optical multiplexers and demultiplexers. An optical multiplexer can be used to combine multiple optical signals to be transmitted at substantially the same time, for example, through a single fiber or waveguide. For example, one type of multiplexer is a wavelength division multiplexer, which combines a number of optical signals, each having different wavelengths, into a single multiplexed signal. An optical demultiplexer, in contrast, can be used to separate a multiplexed signal into a number of individual optical signals, for example, optical signals having different wavelengths.
Conventional packages can be used for a multiplexer or demultiplexer device. For example, a TO-18 package can be used in conjunction with a multiplexer, and a TO-46 package for the demultiplexer. Typically, the laser diodes in the multiplexer, or the photo-detectors in the demultiplexer, take up significant amounts of space in the packages. Consequently, some or all of the other optical components required to multiplex or demultiplex signals may be positioned outside of the packages.